Control device, lens device, imaging device, and method and program for acquiring information regarding focus state

Abstract

To provide a focusing information acquisition device that is advantageous in terms of focusing accuracy, for example.SOLUTION: A focusing information acquisition device includes a detection part which detects at least a part of a light beam from a subject through an optical member, a control part which controls driving of the detection part, and an acquisition part which acquires information on a focusing state based on an output of the detection part. The control part controls the driving of the detection part based on a time change rate of at least one of the information from the output of the detection part and the driving state of the optical member.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a focus information acquisition device, a lens device, an imaging device, a focus information acquisition method, and a program.

Background Art

[0002] As an autofocus (focus information acquisition) technique in an imaging device, there is a technique in which a pair of subject image signals are formed on a sensor from light fluxes that have passed through different regions in an exit pupil. The defocus amount (focus information) of a subject can be acquired based on the relative positions of the pair of subject images.

[0003] In video imaging, it is preferable to control the position of a focus lens unit so as to always maintain a focused state. However, defocus may occur due to the movement of a subject or the driving of a lens unit in an imaging device.

[0004] For example, depending on the focal length of a lens, the depth of the depth of field changes. Therefore, even if the subject distance does not change, the focused state may change.

[0005] Patent Document 1 discloses a technique for improving the followability (immediate responsiveness) to changes in the focused state by shortening the light reception time (for example, charge accumulation time) of a sensor during zooming.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the technology disclosed in Patent Document 1, depending on the brightness of the subject, sufficient signal strength may not be obtained for focus detection (acquisition of focus information) during zooming. Furthermore, while extremely slow zooming is often used for video capture for visual expression, uniformly shortening the light reception time regardless of the zoom speed in this case is undesirable in terms of focusing accuracy.

[0008] The present invention aims to provide a focusing information acquisition device that is advantageous, for example, in terms of focusing accuracy. [Means for solving the problem]

[0009] To achieve the above objective, the focus information acquisition device of the present invention comprises a detection unit that detects at least a portion of the light beam from a subject through an optical member, a control unit that controls the driving of the detection unit, and an acquisition unit that acquires information regarding the focus state based on the output of the detection unit, wherein the control unit controls the driving of the detection unit based on the time rate of change of at least one of the information from the output of the detection unit and the driving state of the optical member. [Effects of the Invention]

[0010] According to the present invention, for example, it is possible to provide a focus information acquisition device that is advantageous in terms of focus accuracy. [Brief explanation of the drawing]

[0011] [Figure 1] Block diagram showing the configuration of the automatic focus adjustment device of the present invention. [Figure 2] Flowchart for determining the phase difference sensor driving conditions [Figure 3] Flowchart for calculating the target storage amount [Figure 4] Flowchart for calculating the storage time [Figure 5] A graph showing the relationship between the drive speed of the zoom lens group and the target storage amount. [Figure 6] Flowchart of the process for calculating the target storage amount in the second embodiment. [Figure 7] Graph showing the relationship between the lens speed evaluation value and the target accumulation amount in the second embodiment [Figure 8] Block diagram showing the configuration of the autofocus adjustment device in the third embodiment [Figure 9] Flowchart of the process for calculating the target accumulation amount in the third embodiment [Figure 10] Graph showing the relationship between the sensitivity change amount and the target accumulation amount in the third embodiment [Figure 11] Flowchart of the process for calculating the target accumulation amount in the fourth embodiment [Figure 12] Graph showing the relationship between the subject movement speed and the target accumulation amount in the fourth embodiment

Mode for Carrying Out the Invention

[0012] Hereinafter, an autofocus adjustment device (focus information acquisition device) according to an embodiment of the present invention will be described in detail based on the accompanying drawings. In each figure, the same components are denoted by the same reference numerals, and redundant descriptions are omitted.

Examples

[0013] Hereinafter, Example 1 of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 shows the configuration of a lens device 100 according to Example 1 of the autofocus adjustment device of the present invention. The lens device 100 allows a light beam that has passed through the optical member 101 to enter the imaging device 107.

[0014] The optical member 101 includes a focus lens group 102, a zoom lens group 103, an aperture .....

[0015] The focus lens group 102 is moved in the optical axis direction by a focus motor (not shown) to change the position of the imaging surface of the lens device 100.

[0016] The zoom lens group 103 moves in the optical axis direction by a zoom motor (not shown) to change the focal length of the lens device 100. The zoom lens group 103 may also be manually operable by an operating member (not shown).

[0017] The aperture 104 is driven by an iris motor (not shown) and limits the beam of light incident on the image sensor 107.

[0018] The spectral prism 105 separates the light that has passed through the focus lens group 102 and the zoom lens group 103 into two beams of light. One beam of light that has passed through the spectral prism 105 passes through the relay lens group 106 and is incident on the image sensor 107. The other beam of light that has been reflected by the spectral prism 105 is incident on the focus detection unit 108.

[0019] The focus detection unit 108 consists of a spectacle lens and a phase difference sensor, and the phase difference sensor converts the pair of images (subject image) (2 images) formed by the two light beams divided by the spectacle lens into photoelectric form.

[0020] The phase difference sensor control unit 109 is a control unit for controlling the phase difference sensor included in the focus detection unit 108. The phase difference sensor control unit 109 determines the set values ​​(phase difference sensor driving conditions) such as the gain and storage time (charge storage time) of the phase difference sensor and drives the phase difference sensor. Increasing the gain increases the amplification ratio of the image signal output from the phase difference sensor, and increases the output value of the signal. Similarly, if the storage time is increased, the time for capturing the image signal input to the phase difference sensor increases, and the output value of the signal also increases. The phase difference sensor control unit 109 determines the next phase difference sensor driving conditions based on the previous phase difference sensor driving conditions, the subject brightness value and contrast value input from the defocus calculation unit 110, and the driving state of the optical element 101 detected by the lens position detection unit 112.

[0021] The defocus calculation unit (defocus amount acquisition unit) 110 calculates the phase difference between a pair of image signals, which are part of the photographic light beam converted photoelectrically by the focus detection unit 108, and calculates the defocus amount. It also calculates the subject brightness value and subject contrast value from the pair of image signals and inputs them to the phase difference sensor control unit 109.

[0022] The lens drive unit 111 controls the focus lens group 102 according to the amount of defocus calculated by the defocus calculation unit 110. The lens drive unit 111 also receives drive commands for the zoom lens group 103 and the aperture 104, and controls the drive of the zoom lens group 103 and the aperture 104, respectively. The drive commands for the zoom lens group 103 and the aperture 104 may be received from the camera or from a controller operated by the user.

[0023] The lens position detection unit 112 independently detects the positions of the focus lens group 102, the zoom lens group 103, the aperture 104, and the relay lens group 106. Position detection means include, for example, an encoder or a potentiometer.

[0024] Figure 2 is a flowchart of the process by which the phase difference sensor control unit 109 determines the phase difference sensor driving conditions. In this embodiment, the autofocus device determines the driving conditions of the phase difference sensor according to the driving speed of the zoom lens group 103 and the subject contrast value. Specifically, the faster the driving speed of the zoom lens group 103, the more frequently focus detection is performed, and the gain and storage time of the phase difference sensor are determined by calculating the amount of accumulation (charge accumulation) required to obtain a sufficient amount of image signal for focus detection.

[0025] In step S201, it is determined whether the results of the previous phase difference sensor drive are available. If they are available, the process proceeds to step S202; otherwise, it proceeds to step S208. Situations in which the results of the previous phase difference sensor drive are unavailable include, for example, the first phase difference sensor drive, or when a predetermined amount of time has elapsed since the previous phase difference sensor drive.

[0026] In step S202, the previous phase difference sensor driving conditions are obtained, and the process proceeds to step S203. Phase difference sensor driving conditions include, for example, gain and storage time.

[0027] In step S203, the subject brightness value calculated by the defocus calculation unit 110 is obtained, and the process proceeds to step S204. The method for calculating the subject brightness value may be the maximum value of the output pixels of the phase difference sensor, or the integral value of the output pixels. Furthermore, the pixel range used for the calculation may be changed according to information such as the distance measurement frame.

[0028] In step S204, it is determined whether the number of saturated pixels is less than a predetermined value (below a threshold). If it is less than the predetermined value, the process proceeds to step S205; if it is greater than or equal to the predetermined value, the process proceeds to step S208. If the output value of the phase difference sensor reaches the maximum level (saturates), correct brightness information cannot be obtained, and appropriate phase difference sensor driving conditions cannot be calculated. Therefore, if the number of saturated pixels is greater than or equal to the predetermined value, the phase difference sensor driving conditions for photometry are set. Although the process of determining the saturation pixel count has been described here, the process of determining the saturation pixel count may also be used, based on whether the subject brightness value is greater than or equal to a predetermined value.

[0029] In step S205, the target storage time is obtained as a target value (threshold) for the storage time, and the process proceeds to step S206. The target storage time may be input by the user, or it may be received from the camera. Alternatively, it may be a predetermined fixed value.

[0030] In step S206, the target storage amount is calculated, and the process proceeds to step S207. The process for calculating the target storage amount will be explained in detail in Figure 3 below.

[0031] In step S207, the gain and storage time are set, and the process proceeds to step S209. The process of setting the gain and storage time will be explained in detail in Figure 4 below.

[0032] In step S208, the gain and storage time are set to fixed values ​​for photometry, and the process proceeds to step S209. The fixed values ​​for photometry are set to, for example, the maximum gain and the shortest storage time, in order to complete the photometry process immediately. Although this example describes fixed values ​​for photometry, a configuration in which the photometry settings are variable may also be used, assuming that subject brightness information cannot be obtained with the desired accuracy even after performing photometry processing multiple times.

[0033] In step S209, the phase difference sensor is driven according to the phase difference sensor driving conditions determined in step S207 or step S208, and its output signal is obtained. The time required to obtain the output signal depends on the storage time determined in step S207 or step S208.

[0034] In step S210, the relative positional relationship (phase difference) of the pair of image signals is determined from the output signal obtained in step S209, and the amount of defocus is calculated from this phase difference before proceeding to step S211. Note that if the driving conditions for the phase difference sensor are set to photometric in step S208, the process from step S210 onward may be omitted and the process may be terminated.

[0035] In step S211, the drive position of the focus lens group 102 is determined from the defocus amount calculated in step S210, and the drive control is performed.

[0036] The process described in Figure 2 is repeated during the execution of the focus adjustment operation. The control cycle mainly depends on the accumulation time of the phase difference sensor. In this embodiment, the target accumulation amount is calculated based on the drive speed of the zoom lens group 103, the subject brightness, and the contrast value, and the accumulation time is determined. This allows for focus adjustment control to be performed in a way that maintains a focus detection accuracy above a certain level while improving the ability to track changes in the focus detection position.

[0037] Figure 3 is a flowchart of the process for calculating the target storage amount in step S206. In step S301, the drive speed of the zoom lens group 103 is calculated based on the position information of the zoom lens group 103 detected by the lens position detection unit 112, and the process proceeds to step S302.

[0038] In step S302, the target accumulation amount is calculated based on the drive speed of the zoom lens group 103, and the process proceeds to step S303. The relationship between the drive speed of the zoom lens group 103 and the target accumulation amount is explained in the graph in Figure 5 (described later).

[0039] In step S303, the subject contrast value calculated by the defocus calculation unit 110 is obtained, and the process proceeds to step S304. The method for calculating the subject contrast value may be, for example, the integral of the absolute difference between adjacent pixels of the output pixels of the phase difference sensor, or the integral of the square of the difference between adjacent pixels. Furthermore, the pixel range used in the calculation may be changed according to information such as the distance measuring frame.

[0040] In step S304, it is determined whether the subject contrast value obtained in step S303 is less than a predetermined value. If it is less than the predetermined value, the process proceeds to step S305; otherwise, the process terminates.

[0041] In step S305, the target accumulation amount obtained in step S302 is updated to a predetermined value, and the process ends. If the subject contrast value is low, the accuracy of the defocus amount calculated by the defocus calculation unit 110 decreases. Therefore, as explained in this example, it is desirable to increase the target accumulation amount obtained in step S302 to improve the accuracy of the output value of the phase difference sensor.

[0042] Figure 4 is a flowchart of the process for setting the gain and storage time in step S207.

[0043] In step S401, the storage time required to obtain the target storage amount calculated in step S206 with a gain of 1x is calculated, and the process proceeds to step S402. The storage time is calculated proportionally from the previous gain and storage time, the subject brightness obtained in step S203, and the target storage amount obtained in step S206. For example, if the previous gain was 2x, the storage time was 1ms, the subject brightness was 100, and the target brightness was 200, the storage time required to obtain the target brightness (200) with a gain of 1x would be 1ms (previous storage time) × 2 (gain ratio) × 2 (brightness ratio) = 4ms.

[0044] In step S402, it is checked whether the storage time calculated in step S401 is less than or equal to the target storage time (below the threshold) obtained in step S205. If it is less than or equal to the target storage time, the process proceeds to step S403; otherwise, the process proceeds to step S404.

[0045] In step S403, the gain is set to 1x and the storage time is set to the storage time calculated in step S401, and then the process ends.

[0046] In step S404, the storage time required to obtain the target storage amount calculated in step S206 with a gain of 2x is calculated, and the process proceeds to step S405. The method for calculating the storage time is the same as in step S401, so the explanation is omitted.

[0047] In step S405, it is checked whether the storage time calculated in step S404 is less than or equal to the target storage time obtained in step S205. If it is less than or equal to the target storage time, the process proceeds to step S406; otherwise, the process proceeds to step S407.

[0048] In step S406, the gain is set to 2x and the storage time is set to the storage time calculated in step S404, and the process ends.

[0049] In step S407, the storage time required to obtain the target storage amount calculated in step S206 with a gain of 4x is calculated, and the process proceeds to step S408. The method for calculating the storage time is the same as in step S401, so the explanation is omitted.

[0050] In step S408, the gain is set to 4x and the storage time is set to the storage time calculated in step S407, and the process ends. Note that if the subject brightness is too low, the storage time may become too long, so if the storage time calculated here exceeds a predetermined value, a process may be added to limit it to within that predetermined value.

[0051] In other words, the phase difference sensor control unit 109 sets the minimum gain that makes it possible to keep the storage time required to obtain the target storage amount below the target storage time. However, if it is not possible to keep the storage time required to obtain the target storage amount below the target storage time, it sets the gain to the maximum possible value. In this way, by setting the minimum gain necessary to obtain the target storage amount under conditions below the target storage time, focus detection can be performed below the target storage time while maintaining detection accuracy.

[0052] Figure 5 is a graph showing the relationship between the drive speed of the zoom lens group 103 and the target storage amount. As shown in Figure 5, in this embodiment, the target accumulation amount is reduced as the driving speed of the zoom lens group 103 increases. When the zoom lens group 103 is driven, the light beam incident on the focus detection unit 108 changes, and the focus detection position (the position of the image in the sensor) changes. Since this amount of change depends on the driving speed of the zoom lens group 103, it is desirable to shorten the focus detection period as the driving speed increases. However, if the accumulation amount falls below a predetermined value, the focus detection accuracy deteriorates significantly, so it is desirable to limit the target accumulation amount so that it does not fall below a predetermined value. In this example, the case in which the target accumulation amount is changed linearly with respect to the driving speed of the zoom lens group 103 has been described, but a configuration in which it is changed non-linearly may also be adopted.

[0053] Lines 501 and 502 in the graph represent the cases in step S304 of Figure 3 where the subject contrast value is determined to be above a predetermined value (normal subject) and below a predetermined value (low-contrast subject), respectively. In this example, the target accumulation amount for low-contrast subjects is always calculated by adding a predetermined value compared to that for normal subjects, but the amount added may be varied depending on the drive speed of the zoom lens group 103.

[0054] As explained above, in this embodiment, the target accumulation amount is varied according to the drive speed of the zoom lens group 103. When the zooming speed is slow, the system is controlled to obtain output with a large accumulation amount, and when the zooming speed is fast, the focus detection period is shortened. Controlling the system to obtain output with a large accumulation amount is advantageous when there is little change in the focus detection position. On the other hand, shortening the focus detection period is advantageous when there is a lot of change in the focus detection position. During zooming, the focus detection position tends to change in proportion to the zooming speed, so controlling the system as described above has the effect of mitigating the delay in focus adjustment.

[0055] Furthermore, instead of limiting the storage time, varying the target storage amount can also maintain a certain level of focus detection accuracy when the subject brightness is low.

[0056] In this embodiment, an example was described in which the target accumulation amount is changed according to the drive speed of the zoom lens group 103, but it is also possible to configure the system so that the target accumulation amount is changed according to the drive speed of the focus lens group 102.

[0057] The autofocus adjustment device of the present invention comprises a detection unit that converts at least a portion of the imaging light beam into photoelectricity, a control unit that controls the driving of the detection unit, and a defocus amount acquisition unit that obtains a defocus amount based on the output of the detection unit. The control unit is characterized in that it controls the accumulation time of the detection unit based on the temporal change (rate of change over time) of a state quantity based on at least one of the output of the detection unit and the driving state of the optical element. [Examples]

[0058] Hereinafter, Embodiment 2 of the present invention will be described with reference to Figures 6 and 7. In this embodiment, components common to Embodiment 1 are denoted by the same reference numerals as in Embodiment 1. Figure 6 is a flowchart of the process for calculating the target storage amount in Example 2. Step S301 is the same as in Figure 3 of Example 1, so its explanation is omitted.

[0059] In step S601, the drive speed of the focus lens group 102 is calculated from the position information of the focus lens group 102 detected by the lens position detection unit 112, and the process proceeds to step S602.

[0060] In step S602, a lens speed evaluation value is calculated from the zoom lens drive speed and focus lens drive speed calculated in steps S301 and S601, and the process proceeds to step S603. The lens speed evaluation value may be, for example, the faster of the zoom lens drive speed and the focus lens drive speed, or it may be the sum of both. Alternatively, the zoom lens drive speed and the focus lens drive speed may each be multiplied by a predetermined coefficient before performing the aforementioned calculation.

[0061] In step S603, the target accumulation amount is calculated according to the lens velocity evaluation value calculated in step S602, and the process proceeds to step S303. The relationship between the lens velocity evaluation value and the target accumulation amount is explained in the graph in Figure 7 (described later).

[0062] Steps S303 to S305 are the same as those shown in Figure 3 of the first embodiment, so their explanation will be omitted.

[0063] Figure 7 is a graph showing the relationship between the lens velocity evaluation value and the target accumulation amount in the second embodiment. As shown in Figure 7, in this embodiment, the lens speed evaluation value is configured to decrease the target accumulation amount as the lens speed evaluation value increases. When the zoom lens group 103 and the focus lens group 102 are driven, the light beam incident on the focus detection unit 108 changes, and the focus detection position changes. Since this amount of change depends on the driving speed of the zoom lens group 103 and the focus lens group 102, it is desirable to shorten the focus detection period as the driving speed increases. In the second embodiment, the lens speed evaluation value is calculated considering the degree of influence of the zoom lens group 103 and the focus lens group 102 on the focus detection position, and the target accumulation amount is configured to be variable. Other aspects are the same as in Figure 5 of the first embodiment, so the explanation will be omitted.

[0064] As described above, in this embodiment, the lens speed evaluation value is calculated according to the drive speed of the zoom lens group and the focus lens group, and the target accumulation amount is controlled. This allows the accumulation amount and control cycle to be changed in consideration of the effect of the operation of each of the multiple optical components on the focus detection position, thereby mitigating the delay in focus adjustment. [Examples]

[0065] A third embodiment of the present invention will be described below with reference to Figures 8 to 10. In this embodiment, components common to Embodiment 1 are denoted by the same reference numerals as in Embodiment 1.

[0066] In Examples 1 and 2, the driving conditions of the phase difference sensor were determined by the driving speed of the lens. However, in this example, we will describe an example in which the driving conditions of the phase difference sensor are determined according to the sensitivity of the lens.

[0067] Figure 8 shows the configuration of the lens device 100 according to Embodiment 3 of the autofocus adjustment device of the present invention. Note that the same components as those in Figure 1 of the first embodiment will not be described.

[0068] Memory 113 is a non-volatile memory such as ROM, and it stores sensitivity information, which is the amount of image plane change (focus sensitivity, image plane change coefficient) per unit movement of the focus lens group 102.

[0069] The sensitivity calculation unit 114 calculates the current sensitivity from the sensitivity information stored in the memory (storage unit) 113, the position information of the focus lens group 102 and the zoom lens group 103, and the defocus amount calculated by the defocus calculation unit 110. The lens drive unit 111 determines the drive amount of the focus lens group 102 from the defocus amount calculated by the defocus calculation unit 110 and the sensitivity calculated by the sensitivity calculation unit 114. In addition, the phase difference sensor control unit 109 determines the next phase difference sensor drive conditions from the previous phase difference sensor drive conditions, the subject brightness value and contrast value input from the defocus calculation unit 110, and the sensitivity calculated by the sensitivity calculation unit 114.

[0070] Figure 9 is a flowchart of the process for calculating the target storage amount in the third embodiment. In step S901, the position information of the focus lens group 102 and the zoom lens group 103 detected by the lens position detection unit 112 is acquired, and the process proceeds to step S902.

[0071] In step S902, the defocus amount calculated by the defocus calculation unit 110 is obtained, and the process proceeds to step S903.

[0072] In step S903, sensitivity is calculated from the position information of the focus lens group 102, the position information of the zoom lens group 103, and the amount of defocus acquired in steps S901 and S902. Furthermore, the change in sensitivity is calculated from the amount of change from the previously calculated sensitivity and the elapsed time, and the process proceeds to step S904.

[0073] In step S904, the target accumulation amount is calculated from the sensitivity change amount calculated in step S903, and the process proceeds to step S303. The relationship between the sensitivity change amount and the target accumulation amount is explained in the graph in Figure 10 (described later).

[0074] Steps S303 to S305 are the same as those shown in Figure 3 of the first embodiment, so their explanation will be omitted.

[0075] Figure 10 is a graph showing the relationship between the change in sensitivity and the target accumulation amount in the third embodiment. As shown in Figure 10, in this embodiment, the target accumulation amount is reduced as the sensitivity change amount increases. When the zoom lens group 103 and the focus lens group 102 are driven, the light beam incident on the focus detection unit 108 changes, and the focus detection position changes. The focus detection position also changes when the subject moves. In the third embodiment, the sensitivity change amount is calculated from the zoom lens group 103, the focus lens group 102 and the defocus amount, and the target accumulation amount is made variable. Other aspects are the same as in Figure 5 of the first embodiment, so the explanation will be omitted.

[0076] As explained above, in this embodiment, the sensitivity change amount is calculated according to the zoom lens group 103, the focus lens group 102, and the defocus amount, and the target accumulation amount is controlled. When the sensitivity changes, the depth of field changes, and therefore the focus detection accuracy changes. As a result, the focus detection position may change even if the distance between the subject and the lens does not change. In this embodiment, since the accumulation amount is controlled according to the change in sensitivity, the focus adjustment control is performed at a high frequency under conditions where changes in the focus detection position are likely to occur, and the delay in focus adjustment can be mitigated. [Examples]

[0077] A fourth embodiment of the present invention will be described below with reference to Figures 11 to 12. In this embodiment, components common to Embodiment 1 are denoted by the same reference numerals as in Embodiment 1.

[0078] In Examples 1 to 3, the driving conditions of the phase difference sensor were determined by the lens driving status. However, in this example, we will describe an example in which the driving conditions of the phase difference sensor are determined according to the subject's moving speed.

[0079] Figure 11 is a flowchart of the process for calculating the target storage amount in the fourth embodiment. In step S1101, the target position (AF drive position) of the focus lens group 102 driven by the lens drive unit 111 is obtained, and the process proceeds to step S1102.

[0080] In step S1102, the subject movement speed is calculated from the AF drive position obtained in step S1101 and the elapsed time since the last AF drive, and the process proceeds to step S1103.

[0081] In step S1103, the target accumulation amount is calculated according to the subject movement speed calculated in step S1102, and the process proceeds to step S303. The relationship between the subject movement speed and the target accumulation amount is explained in the graph in Figure 12 (described later).

[0082] Steps S303 to S305 are the same as those shown in Figure 3 of the first embodiment, so their explanation will be omitted.

[0083] Figure 12 is a graph showing the relationship between the subject movement speed and the target accumulation amount in the fourth embodiment.

[0084] As shown in Figure 12, in this embodiment, the target accumulation amount is reduced as the subject movement speed increases. When the subject movement speed is high, a delay is likely to occur in the focus adjustment operation by the focus lens group 102, so it is desirable to shorten the focus detection period. In the fourth embodiment, the target accumulation amount is made variable according to the detection result of the focus detection unit 108. Other aspects are the same as in Figure 5 of the first embodiment, so the explanation will be omitted.

[0085] As explained above, in this embodiment, the subject movement speed (rate of change in object distance) is calculated from the focus detection position, and the target accumulation amount is controlled, resulting in a configuration that minimizes delays in driving the focus lens group for focus adjustment. When the subject movement speed is fast, the change in the focus detection position becomes large even if the lens drive state does not change. In this embodiment, since the accumulation amount is controlled according to the subject movement speed, focus adjustment control is performed at a high frequency for moving objects, which can mitigate delays in focus adjustment.

[0086] By configuring a lens device having the autofocus adjustment device of the present invention, it is possible to realize a lens device that can enjoy the effects of the present invention.

[0087] Furthermore, by configuring an imaging device that includes a lens device having an autofocus adjustment device of the present invention and an image sensor that captures an image formed by the lens device, an imaging device that can enjoy the effects of the present invention can be realized.

[0088] (Other examples) The present invention can also be realized by supplying a program that implements one or more of the functions (focus information acquisition method) of the above-described embodiment to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0089] Although the present invention has been described above with reference to the examples, the present invention is not limited to the above examples. Inventions modified insofar as they do not contradict the spirit of the present invention, and inventions equivalent to the present invention, are also included in the present invention. Furthermore, the above-described examples and modifications can be combined as appropriate insofar as they do not contradict the spirit of the present invention. [Explanation of symbols]

[0090] 101: Optical components 102: Focusing lens group (optical component) 103: Zoom lens group (optical components) 108: Focus detection unit (detection unit) 109: Phase difference sensor control unit (control unit) 110: Defocus calculation unit (defocus amount acquisition unit)

Claims

1. a detection unit that detects at least a portion of a light beam from a subject via an optical member; a control unit that controls the detection unit based on information based on an output of the detection unit and a moving speed of the optical member; and an acquisition unit that acquires information regarding a focus state based on an output from the detection unit.

2. The control device according to claim 1 , wherein the control unit controls a charge accumulation time in the detection unit.

3. 3. The control device according to claim 1, wherein the optical member moves during at least one of focusing and zooming.

4. A control device as described in any one of claims 1 to 3, characterized in that the information based on the output of the detection unit is information regarding the moving speed of the subject image.

5. 5. The control device according to claim 4, further comprising a storage unit for storing an amount of change in the position of the subject image in response to a change in the position of the optical member.

6. A control device as described in any one of claims 1 to 5, characterized in that the information based on the output of the detection unit is information regarding the defocus amount.

7. A control device as described in any one of claims 1 to 5, characterized in that the information based on the output of the detection unit is information regarding the contrast of the subject image.

8. 8. The control device according to claim 1, wherein the control unit controls the detection unit so that an amount of charge stored in the detection unit does not become less than a threshold value.

9. A control device as described in any one of claims 1 to 8, characterized in that the information based on the output of the detection unit is information regarding the brightness of the subject.

10. The control device according to claim 2 , wherein the control unit controls a gain of the detection unit.

11. A lens device comprising a control device described in any one of claims 1 to 10 and the optical element.

12. 12. An imaging device comprising: a lens device according to claim 11; and an imaging element for capturing an image formed by the lens device.

13. A method for acquiring information regarding a focus state based on an output of a detection unit that detects at least a portion of a light beam from a subject via an optical member, the method comprising: A method for detecting a moving speed of the optical member and controlling the detecting unit based on information from an output of the detecting unit and the moving speed of the optical member.

14. A program causing a computer to execute the method according to claim 13.

Images